private IEnumerable <ItemOrderStats> RetrieveItems(IEnumerable <int> typesToRequest, int regionId, string cacheKey)
{
var resultItems = new List <ItemOrderStats>();
if (!_isServiceAvailable)
{
return(resultItems);
}
var requestUri = new Uri($"https://market.fuzzwork.co.uk/aggregates/?region={regionId}&types={string.Join(",", typesToRequest)}");
var requestTask = _requestProvider.GetAsync(requestUri);
requestTask.Wait(); // wait for the completion (we're in a background task anyways)
if (!requestTask.Result.IsSuccessStatusCode ||
WebServiceExceptionHelper.IsServiceUnavailableError(requestTask.Exception))
{
_isServiceAvailable = false; // TODO: postpone next check.
return(resultItems);
}
if (!requestTask.IsTaskSuccessfullyCompleted())
{
return(resultItems);
}
var contentStreamTask = requestTask.Result.Content.ReadAsStreamAsync();
contentStreamTask.Wait();
using (var reader = new StreamReader(contentStreamTask.Result))
{
try
{
// process result
var retrievedItems = ParseResult(reader.ReadToEnd());
// cache it.
foreach (var item in retrievedItems)
{
_regionDataCache.Add(
ItemKeyFormat.FormatInvariant(item.ItemTypeId, cacheKey),
item,
DateTimeOffset.Now.Add(_cacheTtl));
resultItems.Add(item);
}
}
catch (Exception ex)
{
Trace.TraceError(ex.FormatException());
throw;
}
}
return(resultItems);
}
private Task <IEnumerable <ItemOrderStats> > GetOrderStats(int[] typeIds, int regionId)
{
return(Task <IEnumerable <ItemOrderStats> > .Factory.TryRun(
() =>
{
var cacheKey = regionId.ToInvariantString();
// Get all cached items for the selected region.
var cachedItemStats = typeIds
.Select(typeId => _regionDataCache.Get <ItemOrderStats>(ItemKeyFormat.FormatInvariant(typeId, cacheKey))).ToList();
// Add to the result set not expired items for quered types from cache.
var result = cachedItemStats.Where(item => item?.Data != null && !item.IsDirty).Select(item => item.Data).ToList();
// Get only type IDs that not in the cache.
var typesToRequest = typeIds.Except(result.Select(stats => stats.ItemTypeId)).ToArray();
if (!typesToRequest.Any())
{
return result;
}
result.AddRange(RetrieveItems(typesToRequest, regionId, cacheKey));
// Dirty cached items is better than nothing in the end. Add them to dirty cache in case of no data/error.
var fromDirtyCache = cachedItemStats
.Where(
item => item?.Data != null && item.IsDirty &&
result.Any(resultItem => item.Data.ItemTypeId == resultItem.ItemTypeId))
.Select(item => item.Data);
result.AddRange(fromDirtyCache);
return result;
}));
}
